What charger does iPod A1236 use?

The A1236 model corresponds to a 3rd generation iPod nano.

It can use any USB charger with an appropriate cable. Even new USB-C chargers with an adapter.

It has the old style 30 pin connector though. so you'll need a 3- pin cable to adapter. Apple no longer get makes those.

You can find many on Amazon, for example:

AviBrex USB to 30 Pin Charging Cable 3.3ft 2-Pack - Amazon.com

It didn't fit what? The USB side or the 30 pin side? Please be very clear and detailed about what the issue was.

The wider 30 pin side should connect to the iPod nano's charge port unless the model is wrong or you have some kind of case on the iPod with a different connector.

You'll need to explain what exactly the issue was if you want us to help you. We can't see what you see. Perhaps posting some pictures would also help us understand the problem.